Field of the Invention
The present teaching relates to a method for measuring a height of a surface of an object to be measured, a non-transitory computer readable medium storing a height measuring program, and an height measuring apparatus.
Description of the Related Art
Conventionally, it has been suggested a method for measuring a height as follows (for example, see Japanese Patent Application Laid-open No. H06-201337). That is, a texture pattern is illuminated from above and is projected to a surface of an object via a projection optical system. Then, scanning is performed in a direction of an optical axis of an imaging optical system to obtain a position, at which a degree coming into focus (hereinafter “a degree of focus”) acquired from images detected by an imaging device is maximized, as a height value of the surface of the object.
However, in the conventional measuring method, there is generated a problem such that error is caused in the height value, which is measured depending on an inclination angle of the surface of the object, due to various aberrations such as spherical aberration of the projection optical system and/or the imaging optical system.